1. Field of the Invention
The present invention relates to an aluminum heat exchanger and its manufacturing method where reinforcing plates of the heat exchanger are assembled on both sides in a lamination direction of a core portion having alternating layers of a tube in which liquid flows and a fin improving heat exchange efficiency, and to a jig function when it is brazed.
2. Description of Related Art
When a lamination type heat exchanger having a core portion having alternating layers of a tube and a fin disposed therein is manufactured, an expansion of the core portion by elasticity of the tube and the fin at a temporary assembly before a brazing operation or falling of the fin by declining of elastic holding force of the tube and the fin during the brazing operation under high temperature exist undesirably. Therefore, as shown in FIG. 11, core portion 104 of heat exchanger 100 is fastened and held by jig 105 and band 106 so that the shape of core portion 104 can be maintained until the brazing operation is over. Also as shown in FIG. 12, core portion 104 is fastened and held by winding wire 108 around inserts 107 being fixed at the outside of the outermost fins 102 of core portion 104 so that core portion 104 can retain its shape until the brazing operation is over. In FIGS. 11 and 12, tubes 101 allow liquid to flow therein and sheet metals 103 support both end portions of tubes 101.
Thus, in the manufacturing method of the heat exchanger mentioned above, supporting tools such as jig 105, band 106, and wire 108, etc. are required to maintain the shape of core portion 104 until a brazing operation is over so that operation efficiency becomes bad and the number of working processes increases. Consequently, productivity of core portions declines. Also, since it costs to have jig 105, band 106 and wire 108 which are scrapped after the end of the brazing operation, the cost of the product becomes high.
Thus, in order to eliminate fixing jigs such as jig 105, band 106, and wire 108, a technique where side plates of a core portion having a jig function are pressed and held by a core plate is disclosed in Japanese Examined Patent Publication No. 62-45478. The technique is effective for soldering a core portion of a copper heat exchanger. The fusing point of copper is much higher than that of solder so that copper can maintain a jig function at around the temperature at which solder melts. However, when a core portion of an aluminum heat exchanger is brazed, both fusing points of an aluminum core material and an aluminum blazing filter metal are roughly the same so that the aluminum core material softens around a temperature at which the filter metal melts and looses its jig function. Thus, it is improper to apply the technique mentioned above to an aluminum heat exchanger.
In view of the above problems, it is an object of the present invention to provide a heat exchanger of which a core portion thereof has self-holding function without using special tools during a brazing operation of the core portion in a manufacturing process of an aluminum heat exchanger, and which realizes improved productivity and reduction of product cost of an aluminum heat exchanger.